The invention relates to communication networks. More particularly, the invention relates to an action control point master gatekeeper for use in a communications network.
A communications network can transmit packets of digital information between computers using a protocol, such as Internet Protocol (IP). An increasingly popular use of IP is to transmit audio, video and other multimedia communications between people. For example, a person can use an IP terminal, such as a personal computer connected to an IP network, to speak with another person with an IP terminal. The use of IP terminals to transmit voice communications, similar to the use of a standard telephone, is called IP telephony. As IP networks and IP terminals become faster and more powerful, the use of IP telephony is expected to dramatically increase.
A set of procedures, known as xe2x80x9cH.323,xe2x80x9d are being developed to provide a foundation for audio, video and data communications over IP based networks. The H.323 procedures, such as those dated May 1996, are an umbrella recommendation from the International Telecommunications Union (ITU) to describe terminals, equipment and services for multimedia communication over a Local Area Network (LAN) that does not provide a guaranteed quality of service. Such networks are important because they are commonly used in offices, and include packet-switched Transmission Control Protocol/Internet Protocol (TCP/IP) and Internetwork Packet Exchange (IPX) over Ethernet systems.
FIG. 1 illustrates a communications system, or xe2x80x9czone,xe2x80x9d 100 according to known H.323 procedures. The zone 100 includes a number of xe2x80x9cterminalsxe2x80x9d 110, such as personal computers equipped with microphones and speakers, that provide for real-time, two-way communications with another terminal 110. Each terminal 110 is associated with a terminal address, such as an IP address, which is used to address communications to that terminal 110. According to H.323 procedures, a terminal 110 must provide audio capability, and may also provide video and/or data capabilities, if desired. The terminals 110 communicate with other entities in the zone 100 over a communications network, such as an IP network. The IP network would typically connect, for example, several terminals 110 in a single office.
The zone 100 may include one or more xe2x80x9cgatewaysxe2x80x9d 120, 130 which provide real-time, two-way communications between terminals 110 in the zone 100 and the Public Switched Telephone Network (PSTN). The gateways 120, 130 can also communicate, for example, with another gateway to provide IP telephony with terminals located in another zone (not shown in FIG. 1).
A xe2x80x9cgatekeeperxe2x80x9d 140 provides address translation, control access and, if desired, bandwidth management in the IP network for other H.323 entities in the zone 100. Suppose, for example, a person using a terminal 110 in the zone 100 wants to establish an IP telephony call to a co-worker who also has a terminal in the same zone. The person enters the co-worker""s xe2x80x9cterminal aliasxe2x80x9d using the terminal 110, and the terminal alias is sent to the gatekeeper 140. The terminal alias could be, for example, the co-worker""s name, title, telephone number, e-mail address or Web page. The gatekeeper 140 translates the terminal alias into a terminal address, such as an IP address, associated with the co-worker""s terminal so that the IP telephony call can be established.
As shown in FIG. 1, the zone 100 can include several IP segments that communicate using routers 150. The zone can also include a xe2x80x9cMultipoint Control Unitxe2x80x9d (MCU) 160 which enables three or more terminals 110 and gateways 120, 130 to participate in a multipoint conference. As used herein, the general term xe2x80x9cH.323 entityxe2x80x9d refers to any H.323 component, such as, for example, a terminal 110, a gateway 120, 130, a gatekeeper 140 or an MCU 160. The zone 100 is the collection of H.323 entities and must include at least one terminal 110.
There are several problems with the use of H.323 procedures for IP telephony. One problem is that the procedures cannot be easily xe2x80x9cscaled,xe2x80x9d or applied to larger systems. For example, the gatekeeper 140 must provide address translation for each terminal 110 in the zone 100. If, however, a person wants to contact someone in a different zone, there is no easy way to do this when a large number of users are involved. A person may want to contact one of hundreds of thousands, or millions, of other people using a terminal alias. It is not feasible to have a single gatekeeper 140 translate a terminal alias for that many users. The amount of information that would have to be stored is extremely large, and searching the information would be very time consuming. Moreover, databases for every gatekeeper in every zone would need to be constantly updated when any terminal alias or terminal address, in any zone, was changed. The maintenance and synchronization required for such a task is not practical.
Another disadvantage with the use of H.323 procedures is communications service features associated with traditional telephone service, such as the features provided by a global virtual network service, cannot be provided to IP telephony users. For example, a business may want to prevent some users from placing a telephone call outside of a xe2x80x9cvirtualxe2x80x9d private network, which can include a number of different zones. In the traditional circuit switched network, such a call would be considered an xe2x80x9coff networkxe2x80x9d call.
Suppose a company has offices in New York and Washington, each being supported by a different H.323 zone. The company may want to let an employee in the Washington office call other employees in the Washington office and other employees in the New York office. The gatekeeper for the Washington office, however, would not normally know the terminal alias and terminal address of each employee in the New York office. The problem obviously becomes more acute as more employees, offices and zones are added.
Other communications service features that businesses will expect include, for example, associating a password or client number with a telephone call, voice mail, and the use of calling cards. In addition to businesses, consumers have come to expect such communications service features. Moreover, an IP network carrier will need to be able to introduce new features rapidly to a large number of customers.
Still another drawback with the use of H.323 procedures for IP telephony is that only one gatekeeper 140 is present in each zone 100. If the gatekeeper 140 becomes unavailable, such as, for example, when the computer breaks down, communications in that zone 100 will come to a halt. This will make IP telephony unreliable.
In view of the foregoing, it can be appreciated that a substantial need exists for a method and apparatus allowing for a scalable, reliable and flexible IP telephony system, and for solving the other problems discussed above.
The disadvantages of the art are alleviated to a great extent by an action control point master gatekeeper. In one embodiment of the present invention, an action control point is used in a communications network that has a gatekeeper able to generate an address inquiry, including a terminal alias. The action control point has a customer database that associates the terminal alias with a terminal address. The action control point also has a master gatekeeper that receives the address inquiry and generates an address reply, including the terminal address, based on the association in said customer database.
In this way, the action control point master gatekeeper acts as the glue between zone gatekeepers. A zone gatekeeper will query to the action control point master gatekeeper for address resolution. The action control point can include a centralized database that associates a terminal alias with a terminal address. The master gatekeeper receives the query, with a terminal alias that needs address resolution, from the zone gatekeeper and looks up the terminal address corresponding to the terminal alias. The terminal address is then returned to the zone gatekeeper. If desired, a zone gatekeeper can maintain a local database for the terminals in that zone. In this case, the zone gatekeeper only queries the master gatekeeper when the address is outside of that zone.
In another embodiment of the present invention, the action control point provides a communications service feature based on a requesting terminal identifier in the address inquiry. Such a communications service feature can be provided with the use of, for example, a Network Control Point (NCP).
In this way, the action control point master gatekeeper acts as the glue between a zone gatekeeper and specialized processes, such as NCPs. One example of such an NCP would be for authorization codes. The zone gatekeeper sends an address resolution request to the master gatekeeper. The master gatekeeper realizes that the request needs special processing using a table entry in the master database. The master gatekeeper contacts a NCP process, such as an authorization code NCP process, which in turn requests an authorization code from the end user and verifies the code. The NCP process, such as an authorization code NCP process, returns control to the master gatekeeper, which completes the address resolution by sending a reply to the zone gatekeeper.
In another embodiment of the invention, a master gatekeeper queries another master gatekeeper to resolve an address. An action control point master gatekeeper can be configured with an arbitrary number of zone gatekeepers into an xe2x80x9cadministrative domain.xe2x80x9d A master gatekeeper from one administrative domain can query a higher level master gatekeeper. The higher level administrative domain master gatekeeper queries the master gatekeeper within a second administrative domain. In this way, a hierarchical network of master gatekeepers can be created to allow for scalable networks. A zone gatekeeper makes an address resolution request to a master gatekeeper, which makes a second request to a higher level master gatekeeper. The higher level master gatekeeper can make a third request to another lower level master gatekeeper, which can either access a master database or query the terminating zone gatekeeper. There can be as many levels of master gatekeepers as required by the size of the network.
In still another embodiment, a backup master gatekeeper can be present in the action control point in addition to the normally used, or xe2x80x9cprimary,xe2x80x9d master gatekeeper. A similar backup gatekeeper can be used in a typical H.323 zone. This can be done, for example, by having an action control point master gatekeeper act as a backup zone gatekeeper. Redundant gatekeeper processes can pass queries back and forth so they remain synchronized with the current state of the network at all times.
With these and other advantages and features of the invention that will become hereinafter apparent, the nature of the invention may be more clearly understood by reference to the following detailed description of the invention, the appended claims and to the several drawings attached herein.